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Author Topic: Greenland 2020-21 SMB, melting and GRACE mass  (Read 39950 times)

gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #250 on: August 07, 2021, 09:01:39 AM »
The deniers have crawled out of the woodwork to pounce on a juicy tidbit, being that it is likely that cumulative SMB gain this year (Sept 20 to Aug 21) will be above average.

It prompted me to have a closer look at this warmer, wetter Greenland as evidenced this year.
The attached map shows the accumulated SMB anomaly as at 6 August. What is striking is the difference between the negative anomaly on all the coasts and the positive anomaly on higher ground.

This means that the amount of bare ground at low altitudes will be higher and the glaciers as they approach the sea are likely to experience higher melt. At higher altitudes there have been rain events and melt from insolation that have put large amounts of liquid water into the ice sheet. The scientists tell us that this inputs a lot of heat into the ice sheet. Warmer ice is weaker ice. I am sure there is a lot more negative impacts on the ice sheet - water cascading down moulins to lubricate the contact between the ice and bedrock, for example.

But putting this stuff in front of deniers like the thing identified in a post above is just a waste of time. They have a living to make and denial is their marketing tool.
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anthropocene

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #251 on: August 07, 2021, 10:32:40 AM »

It prompted me to have a closer look at this warmer, wetter Greenland as evidenced this year.
The attached map shows the accumulated SMB anomaly as at 6 August. What is striking is the difference between the negative anomaly on all the coasts and the positive anomaly on higher ground.


Thanks Gerontocrat. I did look at the methodology for producing the SMB figures and it does include rain falling on ice-sheets since this has been found to be accreted to the ice mass-balance (after all the negative impacts listed by Gerontocrat). So having mass balance increase inland (where ice-sheets are thicker and mass balance loss at the coast (with no or thin ice sheets when less water will  be retained) makes sense. So this distribution of mass balance gain/loss is a good indicator of a large percentage of the precipitation being rain rather than snow. Whatever the details, I would contend that rain is one of the best ways to transfer heat to and therefore (eventually) melt ice.

gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #252 on: August 08, 2021, 10:02:49 AM »
7 August Data

Precipitation Above average, entirely in the South and in the North.

Melt Down from 32.8% to 28.4%, not much above average for this day of the year. But note how well it persists in the far North

SMB decreased by 1.4 GT,  well below the average daily SMB loss at this time of year.
_________________________________
Outlook  - The GFS forecast now indicates that the Greenland High is likely to to be stable from now on, but weak enough to allow weather systems to gradually penetrate inland mostly from the South and West.

Precipitation. Stronger signs of weather arriving from the South and especially the West, being a mixture of rain on coasts and snow on higher ground.

Melt looks like gradually moderating or stable from now on for today and Monday. GFS forecasts enough warmth to increase melt significantly from about next Tuesday, and into record territory by next Friday and the follwing weekend (but low probability in forecasts beyond 5 days).

SMB Increasing precipitation may exceed somewhat reduced melt in the next 2 days. After that - totally unsure. High melt and above average precipitation?

Albedo Anomaly Still well below average for the time of year over most of Greenland.

Average daily SMB losses are quickly in decline from now on. My guess remains that the season will end with above average SMB gain for the year.

click images to enlarge
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gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #253 on: August 09, 2021, 11:02:00 AM »
8 August Data

Precipitation Very much above average, entirely in the South, intense on the SE coast, where there was rain on the coastal area.

Melt Down a bit from 28.4% to 27.7%, not much above average for this day of the year.

SMB increased by 1.4 GT,  1st increase since July 14, and very much above what is an average daily SMB loss at this time of year.
_________________________________
Outlook  - The GFS forecast now indicates that the Greenland High is likely to to be stable from now on, but weak enough to allow weather systems to gradually penetrate inland mostly from the South and West.

Precipitation. Stronger signs of weather arriving from the South and especially the West, being a mixture of rain on coasts and snow on higher ground.

GFS predicts an extreme rain event for the entire western half of Greenland next Saturday the 14th Aug. (see next post for images)

Melt looks about the same for today (Monday). GFS forecasts enough warmth to increase melt from about next Tuesday to Thursday. After that temperatures look enough to mean high melt on Friday and an extreme melt event for Saturday and Sunday - i.e.  one for the record books. See next post for images

SMB Increasing precipitation may exceed somewhat reduced melt today (Monday). After that - totally unsure. High melt and above average precipitation?

Average daily SMB losses are quickly in decline from now on. My guess remains that the season will end with above average SMB gain for the year.

click images to enlarge
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gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #254 on: August 09, 2021, 11:09:53 AM »
GFS has persistently been forecasting an extreme temperature and rainfall event for this coming weekend. Indeed, as the days have passed the forecasts have been getting steadily more extreme.

This has persuaded me to post some images of this possible event.

The first 2 images, are of rainfall well inland, the main event being on Saturday.

The 3rd & 4th images are of temperatures next weekend. They imply a truly record two days of melt.

click images to enlarge
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RoxTheGeologist

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #255 on: August 09, 2021, 11:07:18 PM »

It prompted me to have a closer look at this warmer, wetter Greenland as evidenced this year.
The attached map shows the accumulated SMB anomaly as at 6 August. What is striking is the difference between the negative anomaly on all the coasts and the positive anomaly on higher ground.


Thanks Gerontocrat. I did look at the methodology for producing the SMB figures and it does include rain falling on ice-sheets since this has been found to be accreted to the ice mass-balance (after all the negative impacts listed by Gerontocrat). So having mass balance increase inland (where ice-sheets are thicker and mass balance loss at the coast (with no or thin ice sheets when less water will  be retained) makes sense. So this distribution of mass balance gain/loss is a good indicator of a large percentage of the precipitation being rain rather than snow. Whatever the details, I would contend that rain is one of the best ways to transfer heat to and therefore (eventually) melt ice.

There seems to be a lot of river runoff, you can see sediment plumes pretty much everywhere on the coastline.




sidd

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #256 on: August 10, 2021, 08:32:08 AM »
I think the next gravity data release will show more mass loss than currently presumed. But, of course, i could be wrong.

sidd

gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #257 on: August 10, 2021, 10:13:55 AM »
9 August Data

Precipitation Very average

Melt Down a bit from 27.7% to 26.0%, not much above average for this day of the year.

SMB decreased by 2.0 GT,  at the average daily SMB loss at this time of year.
_________________________________
Outlook  - The GFS forecast now indicates that the Greenland High is likely to to be stable and maybe a bit stronger from now on, but weak enough to allow weather systems to gradually penetrate inland mostly from the South and West.

Precipitation. Stronger signs of weather arriving from the South and especially the West, being a mixture of rain on coasts and snow on higher ground.

GFS still predicts an extreme rain event for the entire western half of Greenland next Saturday the 14th Aug.

Melt looks about the same for today (Monday). GFS forecasts enough warmth to increase melt a bit from today (Tuesday) to Thursday. After that temperatures look enough to mean high melt on Friday and now only maybe an extreme melt event for Saturday and Sunday

SMB  - totally unsure. Higher melt and higher precipitation?

Average daily SMB losses are quickly in decline from now on. With growing confidence my guess remains that the season will end with well above average SMB gain for the year.

click images to enlarge
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Eco-Author

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #258 on: August 11, 2021, 03:17:43 AM »
don't want to mess you guys up with a largely data thread but not sure where else to put this... Def. in the category of free-form/brainstorm...  Learned from University Geology lecture that the largest landslide in U.S. history was in SW Utah and although I still cant get my head around it, the geologist that identified this site (millions of years old) said that land slides of that magnitude actually came form just a 1-degree slope... ONE DEGREE... Given all the extra weight of all this incoming rain (what can assumably be many such events to come) and a layered ice sheet, I am compeled to wonder how much of a chance--if any--could the interior greenland ice sheet exhibit this behavior... Perhaps melt and rain water gathering at some intrum layer not making it all the way to the base and just allowing some significant top portion of the ice to slide off??  One thinks of things like an ice sheet or rocky volcano to be all one great big solid mass but every volcano that ever was or will be ends up just being eroded into flatness eventually.  The stress of weight soaking into upper layers of the ice I'd have to assume have a similar potential???  Looks like Augh 14-15 will have one of the largest melt events in Greenland history (staying warm straight through the night) and the rain... Sorry again!

[edit]: The geologist starts to talk about the slope at time mark 39:00...

Source:
« Last Edit: August 11, 2021, 05:09:46 AM by Eco-Author »
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gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #259 on: August 11, 2021, 09:19:21 AM »
10 August Data

Precipitation Very average

Melt Up a bit from 26.0% to 27.0%, not much above average for this day of the year.

SMB decreased by 2.5 GT,  close tothe  average daily SMB loss at this time of year.
_________________________________
Outlook  - The GFS forecast now indicates that the Greenland High is likely to to be stable and maybe a bit stronger from now on, but weak enough to allow weather systems to gradually penetrate inland mostly from the South and West.

Precipitation. Stronger signs of weather arriving from the South and especially the West, being a mixture of rain on coasts and snow on higher ground.

GFS still predicts an extreme rain event for the entire western half of Greenland next Saturday the 14th Aug.

Melt looks about the same for today (Tuesday) to Thursday. After that temperatures look enough to mean high melt on Friday and now GFS temperatures look high enough for an extreme melt event for Saturday through to Tuesday

SMB  - totally unsure. Higher melt and higher precipitation?

Average daily SMB losses are quickly in decline from now on. With growing confidence my guess remains that the season will end with well above average SMB gain for the year despite any extreme melt events.

click images to enlarge
"Para a Causa do Povo a Luta Continua!"
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gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #260 on: August 11, 2021, 09:25:42 AM »
Learned from University Geology lecture that the largest landslide in U.S. history was in SW Utah and although I still cant get my head around it, the geologist that identified this site (millions of years old) said that land slides of that magnitude actually came form just a 1-degree slope... ONE DEGREE... Given all the extra weight of all this incoming rain (what can assumably be many such events to come) and a layered ice sheet, I am compeled to wonder how much of a chance--if any

Some scientists are concerned about the increasing instability of parts of the Greenland ice sheet. Certainly increasing rainfall events, including at higher altitudes, contribute to this instability.

Whether this could ever cause a massively extreme event such as you describe is currently in the realms of pure speculation.

https://www.theguardian.com/environment/2021/may/17/greenland-ice-sheet-on-brink-of-major-tipping-point-says-study
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RoxTheGeologist

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #261 on: August 11, 2021, 04:53:03 PM »
Learned from University Geology lecture that the largest landslide in U.S. history was in SW Utah and although I still cant get my head around it, the geologist that identified this site (millions of years old) said that land slides of that magnitude actually came form just a 1-degree slope... ONE DEGREE... Given all the extra weight of all this incoming rain (what can assumably be many such events to come) and a layered ice sheet, I am compeled to wonder how much of a chance--if any

Some scientists are concerned about the increasing instability of parts of the Greenland ice sheet. Certainly increasing rainfall events, including at higher altitudes, contribute to this instability.

Whether this could ever cause a massively extreme event such as you describe is currently in the realms of pure speculation.

https://www.theguardian.com/environment/2021/may/17/greenland-ice-sheet-on-brink-of-major-tipping-point-says-study

Hydrostatic pressure reduces friction; as the hydrostatic pressure increases to the confining pressure the normal stresses tend to 0, and you are just left with the deviatoric stress.

gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #262 on: August 12, 2021, 09:02:31 AM »
11 August Data

Precipitation A bit above average - a large area of light snow in the Western half of Greenland.

Melt Up from 27.0% to 30.5%, well above average for this day of the year.

SMB decreased by 1.8 GT, close to the average daily SMB loss at this time of year.
_________________________________
Outlook  - The GFS forecast now indicates that the Greenland High is likely to to be stable from now on, but weak enough to allow weather systems to gradually penetrate inland mostly from the South and West.

Precipitation. Stronger signs of weather arriving from the South and especially the West, being a mixture of rain on coasts and snow on higher ground.

GFS still predicts an extreme rain event for the entire western half of Greenland on Saturday the 14th Aug.

Melt looks about the same for today (Wednesday) and Thursday. After that temperatures look enough to mean high melt on Friday and now GFS temperatures look high enough for an extreme melt event for Saturday through to Tuesday.

SMB  - totally unsure. Higher melt and higher precipitation?

Average daily SMB losses are quickly in decline from now on. With growing confidence my prognosis remains that the season will end with well above average SMB gain for the year despite any extreme melt events.

click images to enlarge
"Para a Causa do Povo a Luta Continua!"
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gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #263 on: August 13, 2021, 11:55:24 AM »
12 August Data

Precipitation A bit above average - a large area of light snow on the NW third of Greenland.

Melt Down a bit from 30.5% to 29.2%, well above average for this day of the year.

SMB decreased by 2.2 GT, close to the average daily SMB loss at this time of year.
_________________________________
Outlook  - The GFS forecast now indicates that the Greenland High is likely to to be stable from now on, but weak enough to allow weather systems to gradually penetrate inland mostly from the South and West.

Precipitation. Stronger signs of weather arriving from the South and especially the West, being a mixture of rain on coasts and snow on higher ground.

GFS still predicts an extreme rain event for the entire western half of Greenland on Saturday the 14th Aug, and now a similar event in the South of Greenland on Monday

Melt Temperatures look enough to mean high melt on Friday, i.e. today, and now GFS temperatures look high enough for an extreme melt event for Saturday through to Tuesday.

SMB  - totally unsure. Much higher melt and higher precipitation including significant rain?

Average daily SMB losses are quickly in decline from now on. With growing confidence my prognosis remains that the season will end with well above average SMB gain for the year despite any extreme melt events.

click images to enlarge
"Para a Causa do Povo a Luta Continua!"
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Stephan

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #264 on: August 13, 2021, 09:25:19 PM »
Strong support from www.wetteronline.de about the expected wet and mild period in southern Grønland.
Forecast Aug 13-Aug 26 for Narsarsuaq.
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gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #265 on: August 13, 2021, 11:00:05 PM »
Strong support from www.wetteronline.de about the expected wet and mild period in southern Grønland.
Forecast Aug 13-Aug 26 for Narsarsuaq.
All that heat over Greenland, while just a bit North not a lot in the Arctic Ocean.
Entirely different from 2012 which had record melt in both places.
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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #266 on: August 14, 2021, 04:11:12 AM »
Strong support from www.wetteronline.de about the expected wet and mild period in southern Grønland.
Forecast Aug 13-Aug 26 for Narsarsuaq.

Climate Reanalyzer also showing extreme departures from the norm coming up.

gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #267 on: August 14, 2021, 10:08:41 AM »
13 August Data

Precipitation A bit above average - and a small area of intense precipitation halfway up the West coast, much of it rain - the precursor to today's event?

Melt Up a bit from 29.2% to 31.1%, well above average for this day of the year.

SMB decreased by 1.2 GT, a bit below the average daily SMB loss at this time of year.
_________________________________
Outlook  - The GFS forecast now indicates that the Greenland High is likely to be weak enough to allow weather systems to gradually penetrate inland mostly from the South and West.

Precipitation.  As I write this GFS says an extreme rain event for most of the West of Greenland is happening right now (Saturday the 14th Aug), and manitains a similar event for the South of Greenland on Monday[/i]

Melt And as I write GFS is saying warmth (i.e. above frezing temperatures) is spreading from the South and West to cover all of Greenland apart from the NE corner. i.e. an extreme melt event is happening right now (the 14th August). GFS temperatures also look high enough for a further very high melt from Sunday through to Tuesday or Wednesday.

SMB  - totally unsure. Much higher melt and higher precipitation including significant rain?

Average daily SMB losses are quickly in decline from now on. With growing confidence my prognosis remains that the season will end with well above average SMB gain for the year despite any extreme melt events.

click images to enlarge
"Para a Causa do Povo a Luta Continua!"
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gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #268 on: August 15, 2021, 11:23:55 AM »
14 August Data

Precipitation Extremely above average - intense precipitation over much of West Greenland, much of it rain extending beyond low altitudes

Melt Up from 31.1% to 52.2%, in extreme record territory for this day of the year.

SMB increased by 2.7 GT vs the average daily SMB loss of about 2 GT at this time of year. High precipitation beats high melt every time.
_________________________________
Outlook  - The GFS forecast now indicates that the Greenland High is still likely to be concentrated in the North, thus allowing weather systems to gradually penetrate inland mostly from the South and West.

Precipitation.  Rain & snow for the South on Monday. Overall looks like above average precipitation mainly in the South & West

Melt GFS temperatures also look high enough for a further very high melt from Sunday through to Tuesday or Wednesday.

SMB  - totally unsure. Much higher melt and higher precipitation including significant rain?

Average daily SMB losses are quickly in decline from now on. With high confidence my prognosis remains that the season will end with well above average SMB gain for the year despite any extreme melt events.

click images to enlarge
« Last Edit: August 15, 2021, 10:25:37 PM by gerontocrat »
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Csnavywx

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #269 on: August 16, 2021, 06:37:08 AM »
Dumping ghastly amounts of liquid precip+surface melt into the firn layer. This is exactly the type of event that deeply saturates which then creates frozen hard pan "crust" in winter and increases runoff in subsequent years.

gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #270 on: August 16, 2021, 10:25:58 AM »
15 August Data

Precipitation Extremely above average - over much of West Greenland, less rain and more snow.

Melt Up from 52.2% to 57.5%, in extreme record territory for this day of the year for a 2nd day.

SMB decreased by 0.5 GT vs the average daily SMB loss of about 2 GT at this time of year. High precipitation beats high melt just about every time.
_________________________________
Outlook  - The GFS forecast now indicates that the Greenland High is still likely to be concentrated in the North, thus allowing weather systems to gradually penetrate inland mostly from the South and West.

Precipitation.  Rain & snow for the South on this day - Monday. Overall looks like  precipitation mainly in the South & West

Melt GFS temperatures also look high enough for a further very high melt from Monday through to Tuesday or Wednesday. After that probably moderating.

SMB  - totally unsure. Much higher melt and higher precipitation including significant rain?

Average daily SMB losses are quickly in decline from now on. With high to total confidence my prognosis remains that the season will end with well above average SMB gain for the year despite any extreme melt events.

click images to enlarge
"Para a Causa do Povo a Luta Continua!"
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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #271 on: August 16, 2021, 12:59:47 PM »
These massive rain events over Greenland are a very bad manifestation of climate change, and maybe I haven't been paying enough attention but they seem to have sprung all at once this year.
Even if the rain remains within the ice sheet and contributes to SMB, it destroys albedo and the insulating ability of the ice sheet, lubricates the movement of the ice, and I'm sure also a multitude of other issues, none of them good.

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #272 on: August 16, 2021, 05:21:18 PM »
Between these developments and the near-meltout of the Greenland Sea, as well as the poor condition of the ice NE of the island, the region has been having quite an interesting (and unfortunate) year, despite the plodding progression of the Pacific side of the Arctic.

I wonder if this late-season high melt combined with the major rain events will have effects that start to become visible in the near future (within the next few years)

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #273 on: August 16, 2021, 05:55:17 PM »
Basing this even on the number of melt days doesn't seem accurate, as GFS had the melt getting even worse STRAIGHT through the dead of night; when usually melt is only a few hours in the high afternoon (not to mention the peak temps seem much higher than just simply above freezing)!  What little worldview showed of the West coast was glowing light blue and one can only imagine river like surges down onto the fractured parts of the glacier.  Similarly, one can guess that those mulons (sp?) were channeling not just zero degree melt water deep into the ice, but 40-F degree rain ontop of more rain channeled far warmer water down into the base of the ice than usual.  The reason we're all worried about the loss of sea ice is its effect on Greenland as well as the Clathrate Gun and in both of those cases (with Laptev having--arguably--its worst year, and now this event... seems far worse than breaking sea ice records as Glaciers don't need to melt to raise sea levels... they just have to be flushed out to sea!  Get some Hurricane Harvey 55" of rain hitting Greenland one day... I'd call that game over! 
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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #274 on: August 16, 2021, 08:23:24 PM »
I haven't been paying much attention to Greenland this year, but this is insane...  :o
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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #275 on: August 16, 2021, 10:09:01 PM »
Very interesting and worrying.
The precipitation has not reached the eastern coast of Grønland, as you can see on the latest webcam picture from Freya Gletscher. Temperatures well above +5°C, even over night. Almost no snow left. No comparable "bare ice" picture available for an Aug 16 as far as the data goes back (2016)...
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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #276 on: August 17, 2021, 12:17:10 AM »
Very interesting and worrying.
The precipitation has not reached the eastern coast of Grønland, as you can see on the latest webcam picture from Freya Gletscher. Temperatures well above +5°C, even over night. Almost no snow left. No comparable "bare ice" picture available for an Aug 16 as far as the data goes back (2016)...
The Greenland high in the North to NE is blocking any precipitation from reaching the NE, and it seems it's likely to stay that way for some time.
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gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #277 on: August 17, 2021, 11:30:27 AM »
No update by DMI this morning

bummer.
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Eco-Author

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #278 on: August 17, 2021, 07:38:46 PM »
Please feel free to put this in the appropriate thread (Alison GL in the central NW~) DOUBLY sorry for not knowing how to edit out all the cloudy days but this is one of two Glaciers I see surging forth... The bottom one seems to have surged forth 5+km (not seeming like clouds) filling in what was only on the 8th well behind the black line to being well out ahead of it.  The other was in the central South East but so far doesn't seem like a huge difference in regards to other primary glaciers...?!  ECMWF (in eight days)??  WOW!! 

{edit} just screen captured to be less confusing!
« Last Edit: August 17, 2021, 07:46:30 PM by Eco-Author »
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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #279 on: August 18, 2021, 10:19:02 AM »
No Greenland update today from DMI.

Yesterday I wrote to DMI and here is the answer...

Quote
Martin Stendel
Tue, 17 Aug, 21:56 (11 hours ago)
to me

On 17.08.21 21:22, Matthew Greenwood wrote:
> DMI, do you have a problem?

Yes, we do. There is a problem with the routines for the surface mass balance on the Polar Portal.
We are collecting the data and redo the run in question. We expect to be back to normal conditions tomorrow. I have also written a note on Twitter.

Thanks for your patience
Martin Stendel
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gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #280 on: August 18, 2021, 11:00:38 PM »
DMI back online.

16 August data

It's very late so just one line - precipitation in the west, very high melt giving an above avaerge SMB loss.

+ images - click to enlarge
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gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #281 on: August 18, 2021, 11:02:35 PM »
DMI back online.

17 August data

It's very late so just one line - precipitation in the west, very high melt giving a very much above average SMB loss.

+ images - click to enlarge
[/quote]
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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #282 on: August 19, 2021, 12:51:05 AM »
Rain fell at Summit Station on 14th August 2021.

August 14, 2021, rain was observed at the highest point on the Greenland Ice Sheet for several hours, and air temperatures remained above freezing for about nine hours. This was the third time in less than a decade, and the latest date in the year on record, that the National Science Foundation’s Summit Station had above-freezing temperatures and wet snow

https://nsidc.org/greenland-today/2021/08/rain-at-the-summit-of-greenland/

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #283 on: August 19, 2021, 03:17:27 PM »
18 August Data

Precipitation Perhaps average - over West Greenland, rain in the south.

Melt Down a bit from 46.9% to 45.6%, in record territory for this day of the year.

SMB decreased by 5.9GT vs the average daily SMB loss of 2 GT or less at this time of year. Note the intense SMB loss on the West caost and some way inland..
_________________________________
Outlook  - The GFS forecast now indicates that the Greenland High is still likely to be concentrated in the North, thus allowing weather systems to gradually penetrate inland mostly from the South and West.

Precipitation.  Maybe some dryer days in the next 3-5 days. Overall looks like  precipitation mainly in the South & West, a mixture of rain and snow.

Melt Probably moderating over the next few days. GFS temperatures indicate a final(?) blast of melt next Tuesday/Wednesday.

SMB  - I am totally unsure on losses or gains in the next few days. But average daily SMB losses are quickly in decline from now on. With slightly lower confidence my prognosis remains that the season will end with well above average SMB gain for the year despite any extreme melt events.

click images to enlarge
« Last Edit: August 19, 2021, 04:33:09 PM by gerontocrat »
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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #284 on: August 19, 2021, 08:42:15 PM »
Rain fell at Summit Station on 14th August 2021.

August 14, 2021, rain was observed at the highest point on the Greenland Ice Sheet for several hours, and air temperatures remained above freezing for about nine hours. This was the third time in less than a decade, and the latest date in the year on record, that the National Science Foundation’s Summit Station had above-freezing temperatures and wet snow

https://nsidc.org/greenland-today/2021/08/rain-at-the-summit-of-greenland/

It was really a major event. Dew point was also positive at Summit (it was not the case in 1995 and 2012). This was one of the largest melt event, and a prodigious amount of rain (again, rain, liquid water...) felt:

https://twitter.com/xavierfettweis/status/1426810172685574146
https://twitter.com/xavierfettweis/status/1426450484932587520

As a result, the anomaly of the SMB turns negative:

https://www.climato.uliege.be/cms/c_5652668/fr/climato-greenland

It is really an extraordinary event...
« Last Edit: August 19, 2021, 08:57:03 PM by aslan »

gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #285 on: August 20, 2021, 07:55:32 AM »
Re: The post by aslan above - a tale of two models

The output from the MAR model produced by Feitweiss is showing SMB balance for the year  currently at about 50GT below the 1981-2010 mean.

The output from the HARMONIE-AROME weather model produced by DMI is showing SMB balance for the year currently at about 50GT above the 1981-2010 mean.

The DMI output seems to be more conservative about run-off.

One has to choose a model and stick with it. So I have to stay with the DMI model
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gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #286 on: August 20, 2021, 08:19:16 AM »
19 August Data

Precipitation below average - patches over West Greenland.

Melt Down a bit from 45.6% to 41.9%, in record territory for this day of the year.

SMB decreased by 4.8GT vs the average daily SMB loss of 2 GT or less at this time of year. Note the continued intense SMB loss on the West coast and some way inland..
_________________________________
Outlook  - The GFS forecast now indicates that the Greenland High is still likely to be concentrated in the North but weakening aftern 5 days or so, thus allowing weather systems to gradually penetrate inland mostly from the South and West.

Precipitation.  Maybe some dryer or very dry days in the next 3-5 days. Overall looks like  precipitation mainly in the South & West, a mixture of rain and snow.

Melt Probably moderating over the next few days. GFS temperatures indicate a final(?) blast of melt next Tuesday/Wednesday.

SMB  - I am totally unsure on losses or gains in the next few days. But average daily SMB losses are quickly in decline from now on. With slightly lower confidence my prognosis remains that the season will end with well above average SMB gain for the year despite any high melt events.

click images to enlarge
"Para a Causa do Povo a Luta Continua!"
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gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #287 on: August 21, 2021, 08:45:07 AM »
20 August Data

Precipitation much below average - patches over coastal SE Greenland.

Melt Down a bit from 41.9% to 38.5%, still in record territory for this day of the year.

SMB decreased by 3.8GT vs the average daily SMB loss of 2 GT or less at this time of year. Note the continued intense SMB loss on the West coast and some way inland..
_________________________________
Outlook  - The GFS forecast now indicates that the Greenland High is still likely to be concentrated in the North & East  and gradually strengthening.

Precipitation.  Maybe some dryer or very dry days for the next 3-5 days or even longer. Overall looks like  precipitation mainly in the South & West, a mixture of rain and snow.

Melt Probably moderating over the next few days. GFS temperatures indicate a final(?) blast of melt next Tuesday/Wednesday.

SMB  - I am totally unsure on losses or gains in the next few days. But average daily SMB losses are quickly in decline from now on. With slightly lower confidence (each day) my prognosis remains that the season will end with well above average SMB gain for the year despite any high melt events.

click images to enlarge
"Para a Causa do Povo a Luta Continua!"
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gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #288 on: August 22, 2021, 11:50:25 AM »
21 August Data

Precipitation  below average - quite intense on the far SE coast where it included rain.

Melt Down a bit from 38.5% to 37.5%, still in record territory for this day of the year.

SMB decreased by 2.0GT vs the average daily SMB loss which is close to zero at this time of year. Note the continued intense SMB loss on the West coast and some way inland..
_________________________________
Outlook  - The GFS forecast now indicates that the Greenland High is still likely to be concentrated in the North & East.

Precipitation.  Maybe some dryer or very dry days for the next 3-5 days or even longer. Now overall looks like  precipitation mainly in the South-east, a mixture of rain and snow.

Melt Probably moderating over the next 2 days. GFS temperatures indicate a final(?) above average melt next Tuesday/Wednesday and diminishing day by day after that.

SMB  - I am totally unsure on losses or gains in the next few days. But average daily SMB losses are at about zero now and switch to daily gains from now on. My prognosis remains that the season will end with well above average SMB gain for the year despite any high melt events.

click images to enlarge
"Para a Causa do Povo a Luta Continua!"
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gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #289 on: August 23, 2021, 11:19:18 AM »
22 August Data

Precipitation  below average

Melt Down from 37.5% to 29.4%, very much above average for this day of the year.

SMB decreased by 2.8GT vs the average daily SMB loss which is close to zero at this time of year. Note the continued intense SMB loss on the West coast and some way inland..
_________________________________
Outlook  - The GFS forecast now indicates that the Greenland High is still likely to be concentrated in the North & East.

Precipitation.  Maybe some dryer or very dry days for the next 3-5 days or even longer. Now overall looks like  precipitation mainly in the southeast, a mixture of rain and snow.

Melt Probably moderate today. GFS temperatures indicate a final(?) above average melt  Tuesday/Wednesday and diminishing day by day after that.

SMB  - I am totally unsure on losses or gains in the next few days. But average daily SMB losses have switched to daily gains from now on. My prognosis remains that the season will end with well above average SMB gain for the year despite any high melt events.

click images to enlarge
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gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #290 on: August 24, 2021, 12:12:07 PM »
23 August Data

Precipitation  below average

Melt Down from 29.4% to 20.6%, still very much above average for this day of the year.

SMB decreased by 3.1GT vs the average daily SMB small gain at this time of year. Note the continued SMB loss on the West coast and some way inland.
Given the lower melt, one wonders if the DMI model assumes continued run-off from previous days' record melt?
_________________________________
Outlook  - The GFS forecast now indicates that the Greenland High is still likely to be concentrated in the North & East and may strehgthen after a few days

Precipitation.  Maybe some dryer or very dry days for the next 3-5 days or even longer. Now overall looks like  precipitation mainly from the south, and falling mainly in the southeast, a mixture of rain and snow.

Melt GFS temperatures indicate a final(?) above average melt  Today/Wednesday and moderating after that.

SMB  - I am totally unsure on losses or gains in the next few days. But average daily SMB losses have switched to daily gains from now on. My prognosis remains that the season will end with well above average SMB gain for the year despite any high melt events.

click images to enlarge
« Last Edit: August 24, 2021, 12:20:07 PM by gerontocrat »
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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #291 on: August 24, 2021, 12:48:21 PM »
Given the lower melt, one wonders if the DMI model assumes continued run-off from previous days' record melt?

Makes sense, once the water has melted and starts flowing in rivers it's much harder to make it freeze back up before reaching the coast. But the travel time to the coast could take several days nonetheless.

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #292 on: August 24, 2021, 04:27:30 PM »
"Groundwater", even that which is found in soggy ice, can take quite some time to flow through the "ground" before finding its way to supra- or sub-glacial streams and rivers.  This must be fascinating to study!  (My father was a ground water consultant for many years, but I only have a long-time-ago undergraduate geology student's rusty knowledge.)
Arctic ice is healthy for children and other living things.

gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #293 on: August 24, 2021, 04:57:21 PM »
So I asked DMI if the Watson River discharge was showing the impact.
They sent me a link

https://twitter.com/DirkvanAs/status/1429551660884537350
Watson River has a lot of meltwater running through it these days. It drains a large sector of the Greenland ice sheet, which has been hit by a serious melt event.

Which has a video.

https://twitter.com/i/status/1429551660884537350

What annoys me is that the flows at Watson River have been monitored on a 6 hour cycle continuously from 2006 - but we don't see the data except on a graph at least one year later.
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gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #294 on: August 25, 2021, 09:59:08 AM »
24 August Data

Precipitation average, mostly on the SE coast

Melt Up from 20.6% to 23.9%, still very much above average for this day of the year, but less than I anticipated from GFS temperatures.

SMB decreased by 1.5GT vs the average daily SMB small gain at this time of year. Note the continued SMB loss on the West coast and some way inland.
Given the lower melt, one wonders if the DMI model assumes continued run-off from previous days' record melt? From the posts above, the answer looks like yes.
_________________________________
Outlook  - The GFS forecast now indicates that the Greenland High is still likely to be concentrated in the North & East

Precipitation.  Maybe some dryer or very dry days for the next 3-5 days or even longer. Now overall looks like  precipitation mainly from the south, and falling mainly in the southeast, a mixture of rain and increasingly snow.

Melt GFS temperatures indicate a final(?) above average melt today (Wednesday) and moderating after that.

SMB Average daily SMB losses have switched to daily gains from now on. My prognosis remains that the season will end with above average SMB gain for the year despite any high melt events.

click images to enlarge
"Para a Causa do Povo a Luta Continua!"
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gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #295 on: August 26, 2021, 01:51:47 PM »
25 August Data

Precipitation above average

Melt Up from 23.9% to 29.2%, looking like record territory for this day of the year, but less than I anticipated from GFS temperatures a few days ago.

SMB increased by 0.3GT in line with  the average daily SMB small gain at this time of year. Note the continued SMB loss on the West coast and some way inland.
_________________________________
Outlook  - The GFS forecast now indicates that the Greenland High is still likely to be concentrated in the North & East, and in the longer forecast becoming strong, linked to a high over NW Europe and a high over NE Canada.

Precipitation.  Maybe some dry days for the next 3-5 days or even longer. Now overall looks like  precipitation mainly from the south, and falling mainly in the southeast, a mixture of rain and increasingly snow.

Melt GFS temperatures indicate moderating day by day.

SMB Average daily SMB losses have switched to increasing daily gains from now on. My prognosis remains that the season will end with above average SMB gain for the year despite any high melt events.

click images to enlarge
"Para a Causa do Povo a Luta Continua!"
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gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #296 on: August 27, 2021, 12:12:07 PM »
26 August Data

Precipitation  average mainly in the West

Melt Down from 29.2% to 25.1%, still looks like record territory for this day of the year.

SMB decreased by 1.2T in contrast with  the average daily SMB small gain at this time of year. Note the continued SMB loss on the West coast and some way inland, though declining.
_________________________________
Outlook  - The GFS forecast now indicates that the Greenland High is still likely to be concentrated in the North & East, and in the longer forecast becoming stronger. The longer-term forecast is highly variable.

Precipitation.  Maybe some dry days for the next 3-5 days. Now overall looks like  precipitation mainly from the south, and falling mainly in the southeast, a mixture of rain and increasingly snow, with occasional weather in the West from Baffin Bay.

Melt GFS temperatures indicate moderating day by day.But GFS agian forecasts warmth in the south for Tuesday to Thursday next week sufficient for a significant uptick in melting.

SMB Average daily SMB losses have switched to increasing daily gains from now on. My prognosis remains that the season will end with above average SMB gain for the year despite any high melt events.

The DMI Greenland year finishes on Aug 31. Appreciable melt already lasts even into October. Maybe this year appreciable SMB losses will also occur at least in the beginning of September.
Global heating means welcome to a warmer wetter Greenland and a prolonged summer?

click images to enlarge
"Para a Causa do Povo a Luta Continua!"
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gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #297 on: August 28, 2021, 03:16:46 PM »
27 August Data

Precipitation  very much above average from the SE

Melt Down from 25.1% to 20.3%, still very much above for this day of the year.

SMB increased by a very high 3.3GT in contrast with  the average daily SMB small gain at this time of year. Note the continued SMB loss on the West coast and some way inland, though now declining very quickly.
_________________________________
Outlook  - The GFS forecast now indicates that the Greenland High is still likely to be concentrated in the North & East, and in the longer forecast becoming stronger. The longer-term forecast is highly variable.

Precipitation.  Maybe some dry days for the next 3-5 days. Now overall looks like  precipitation mainly from the south, and falling mainly in the southeast, a mixture of rain and increasingly mostly snow, with occasional weather in the West from Baffin Bay.

Melt GFS temperatures indicate moderating day by day. The GFS  forecast for warmth in the south for Tuesday to Thursday next week now only sufficient for a modest uptick in melting.

SMB Average daily SMB losses have switched to increasing daily gains from now on. My prognosis remains that the season will end with above average SMB gain for the year despite any now unlikely high melt events. Indeed it may be that the SMB gain for the year on the 26th August may be the lowest point for the year end.

click images to enlarge
"Para a Causa do Povo a Luta Continua!"
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gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #298 on: August 28, 2021, 07:45:19 PM »
https://podaac-tools.jpl.nasa.gov/drive/files/allData/tellus/L4/ice_mass/RL06/v02/mascon_CRI

Greenland Ice Sheet Mass Change - GRACE & GRACE-FO data from JPL

We have a monthly update to mid-June 2021.

The first graph combines SMB data from DMI with Overall Mass Change from JPL. From that arithmetic determines the mass loss from the calving and the melting of marine-terminating glaciers.
Note:
Thus GRACE data can give no insight as to the accuracy or otherwise of DMI SMB data.
Also data from other SMB models (e.g. MAR) would give a different figure for the mass loss from the calving and the melting of marine-terminating glaciers.

The data so far this year to mid-June gives no real surprises. However, since then it has been quite an intense melting season, and though precipitation has been above average, there have been many rain on snow events. Add to that Baffin Bay's relative early melt, and Greenland Sea ice at record lows, maybe for July, August and September we will see large Greenland mass losses and espcially from calving and glacial melting.
____________
The second graph shows Greenland Mass change from 2002 to the latest measurement from GRACE & GRACE-FO data. SMB gains during winter to early summer often exceeed glacial melting and calving. Fom sometime in June to sometime in September SMB losses plus melting and calving should produce a significant Greenland mass loss.
"Para a Causa do Povo a Luta Continua!"
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gerontocrat

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Re: Greenland 2020-21 SMB, melting and GRACE mass
« Reply #299 on: August 29, 2021, 12:19:28 PM »
28 August Data

Precipitation  Above average from the SE and mostly snow.

Melt Down from 20.3% to 17.6%, which is still very much above for this day of the year.

SMB increased by 1.8GT somwhat above the average daily SMB small gain of around 1GT at this time of year. Note the continued SMB loss on the coastal fringe and some way inland, though now declining very quickly.
_________________________________
Outlook  - The GFS forecast now indicates that the Greenland High is likely to strengthen then weaken, but the GFS forecast of the timing and strength of events changes every day.

Precipitation.  Maybe some dry days for the next 3-5 days. Now overall looks like  precipitation mainly from the south, and falling mainly in the southeast, a mixture of rain and increasingly mostly snow, with occasional weather in the West from Baffin Bay.

Melt GFS temperatures indicate melt moderating day by day. The GFS  forecast for warmth in the south for Tuesday to Thursday next week now only sufficient for a modest uptick in melting.

SMB Average daily SMB losses have switched to increasing daily gains from now on. Indeed it may be that the SMB gain for the year on the 26th August may be the lowest value of SMB gain at the year end.

click images to enlarge
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)